FIG. 27 illustrates an example of a conventional semiconductor light emitting device. In a semiconductor light emitting device 9 of the same drawing, a lead 92 is formed at a base member 91. A Light Emitting Diode (LED) chip 93 is mounted on the lead 92. The LED chip 93 includes a semiconductor layer 94 and a sub mount substrate 95. The semiconductor layer 94, for example, includes an n-type semiconductor layer, a p-type semiconductor layer, and an active layer disposed therebetween. The sub mount substrate 95 supports the semiconductor layer 94. The sub mount substrate 95 is formed of, for example, Si. The LED chip 93 is electrically connected to the lead 92 by a wire 96. A sealing resin 97 covers the LED chip 93, and transmits light from the LED chip 93.
When the LED chip 93 emits light, heat is mainly generated from the active layer. The heat is dissipated by being transferred to the lead 92 and the base member 91. However, the sub mount substrate 95 is interposed between the active layer and the lead 92. The sub mount substrate 95 prevents heat from being dissipated from the LED chip 93. Due to this reason, there is a problem in that light emission efficiency of the LED chip 93 is reduced.
FIG. 28 illustrates another example of a semiconductor light emitting device (for example, see Japanese Patent Application Laid-Open No. 2004-119743). In a semiconductor light emitting device 900 of the same drawing, an LED chip 902 is mounted on a base member 901. The LED chip 902 is surrounded by a reflector 905 having a frame shape. A space surrounded by the reflector 905 is filled with a sealing resin 906. The LED chip 902, for example, includes a sub mount substrate 903 formed of Si and a semiconductor layer 904 stacked on the sub mount substrate 903. The semiconductor layer 904 is electrically connected to the base member 901 through the sub mount substrate 903.
Light, emitted sideways from the LED chip 902, is reflected in an upward direction by the reflector 905. To emit more reflected light from the semiconductor light emitting device 900, an inner wall surface of the reflector 905 may be greatly inclined from an angle perpendicular to the substrate 901. However, as the inner wall surface is inclined, the semiconductor light emitting device 900 is enlarged. Miniaturizing of the semiconductor light emitting device 900 is strongly desired because electronic devices including the semiconductor light emitting device 900 have space restrictions. Due to this reason, it is difficult to simultaneously realize miniaturization and high luminance of the semiconductor light emitting device 900.